Abstract
Nanomaterial such as metals and metal oxide photocatalysts have emerged as important tools for removing contaminants from wastewater and as antibacterial agents to prevent infections; this is mainly due to their stability under different irradiation conditions. Herein, the catalytic and antimicrobial activities of nanocrystalline silver (Ag), supported on tungsten oxide (WO3) nanoparticles prepared using the deposition-precipitation synthesis technique, are studied. The synthesized material was characterized as XRD, XPS, TEM, and TEM-EDS to investigate their physio-chemical properties. HRTEM, XPS analysis shows that the photocatalyst has a large sheet-like morphology with well-dispersed small metallic Ag particles (<3 nm) on the WO3 nanoparticle's surface, with most particles near the edges. Ultraviolet–visible spectra analysis observed a large redshift in the absorbing band edge and decreased bandgap energy from 2.6 to 2.1 eV. Photocatalytic analysis at different concentrations of 1% Ag/WO3 under visible light indicated a high degradation efficiency. The largest degradation efficiency of Methylene Blue (MB) under visible light irradiation was (∼80%) in 120 min at 1 g/L catalyst dosage. The photodegradation of MB under visible light as a function of catalyst dose followed the pseudo-first-order kinetics. In addition, the catalyst shows high degradation efficiency and significant dose-dependent inhibition of Gram-negative E. Coli and the Gram-positive S. aureus. Furthermore, the catalyst showed excellent stability and recyclability.
Highlights
Recent studies suggest that contaminants such as pharmaceuticals, phenolic compounds, and dyes are found in water sources, while mi croorganisms grow in water and on surfaces
Selected area electron diffraction (SAED) (Fig. 3(c)) was performed to confirm the existence of Ag in WO3 further, which clearly showed the existence of a combination of the spots, as observed in Fig. 3 (c), where the more substantial spot is attributed to underlying crystalline WO3, confirming the presence of well-crystallized Ag parti cles [31]
Visible light irradiation allows electrons in the valence band (VB) to transfer into the conduction band (CB)
Summary
Recent studies suggest that contaminants such as pharmaceuticals, phenolic compounds, and dyes are found in water sources, while mi croorganisms grow in water and on surfaces. Several metallic elements have been used as a dopant to modify the electronic structure and sur face properties of WO3, extending their visible light region absorbance and the photocatalyst’s lifetime This process is achieved by trapping photogenerated electrons to create valence band (VB) holes that oxidize the organic molecules rather than consuming them in a recombination reaction [19,20]. The synthesized material acts as an antimicrobial to inhibit bacteria and viruses under ambient light and dark conditions to remove microorganisms from water resources and surfaces and pro tect people against growing infectious diseases This process is green and based on bio-mimicking photosynthesis by employing visible light (sunlight or ambient light), photocatalysis, and nanotechnology
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